Bulgarian authorities have identified 15 people and made six arrests so far in relation to the racist abuse of England players on Monday night.

England’s black players were targeted throughout the match in Sofia, and the Bulgarian Football Union has been charged by UEFA over the racist behaviour of its fans.

Commissioner of the Bulgarian ministry of the interior Georgi Hadzhiev confirmed the operation was still ongoing, but that action was being taken against those found to have been involved.

In a statement on Wednesday afternoon, the ministry confirmed “15 participants were identified in the unlawful event”, with some of the evidence collected using facial recognition software.

The ministry statement said: “Six of them have been detained and three are wanted, two have been summoned and are expected to report to the police to testify. Work is under way to gather evidence for the other six.

“The materials will be reported to the Sofia District Prosecutor’s Office.”

Hadzhiev added his condemnation of the culprits, saying: “We do not tolerate such behaviour. All violators of the public order will be summoned (by the authorities).”

Earlier, a spokeswoman for the ministry told the PA news agency four males had been detained following the initial investigations.

The spokeswoman also confirmed that special forces from the ministry’s general directorate for combating organised crime had raided the BFU offices on Tuesday.

The BFU’s president, former national team goalkeeper Borislav Mihaylov, announced his resignation in the wake of Monday night’s racist chanting.

Under the UEFA regulations, the BFU could face a full ground closure for their next competitive home match and a fine of 50,000 euros.

Aleksander Ceferin, the president of European football’s governing body, spoke on Tuesday about ‘waging war’ on racism.

Under Article 14 of UEFA’s disciplinary code which relates to racism, there is scope to impose a tougher sanction such as points deduction or even disqualification “if the circumstances of the case require it”.

FIFA president Gianni Infantino also suggested any penalties imposed would be extended worldwide. He said football needed “new, stronger and more effective ways to eradicate racism in football” and called for life bans from stadiums for any individuals found guilty of racist behaviour.

Ceferin said on Tuesday: “UEFA’s sanctions are among the toughest in sport for clubs and associations whose supporters are racist at our matches. The minimum sanction is a partial closure of the stadium – a move which costs the hosts at least hundreds of thousands in lost revenue and attaches a stigma to their supporters.

“UEFA is the only football body to ban a player for 10 matches for racist behaviour – the most severe punishment level in the game. Believe me, UEFA is committed to doing everything it can to eliminate this disease from football. We cannot afford to be content with this; we must always strive to strengthen our resolve.

“More broadly, the football family – everyone from administrators to players, coaches and fans – needs to work with governments and NGOs to wage war on the racists and to marginalise their abhorrent views to the fringes of society.

“Football associations themselves cannot solve this problem. Governments too need to do more in this area. Only by working together in the name of decency and honour will we make progress.”

Football Association chairman Greg Clarke said on Monday night that a stringent review was required into the events in Sofia and that “zero tolerance” had to be shown towards racist behaviour.

He told ITV Sport: “UEFA are going to have to think very carefully about the level of abuse they’re prepared to let players tolerate and they’re going to have to decide who they are going to make an example of one day, but that’s after a thorough examination of the facts.”

England rugby player Maro Itoje, currently representing his country at the World Cup in Japan, offered his opinion on Monday’s events.

“It’s appalling to be honest. It’s just appalling. It’s abysmal,” he said.

“You would think that they wouldn’t have to go through that. It sends a poor message about the game of football.

“It’s a shame because it’s such a beautiful game and it’s being tarred by people with racist thoughts and racist minds.

“It’s terrible that they have to experience that when they just want to go out and play the game they love.

“I’m very happy that for the most part in rugby there’s a different climate and that kind of stuff doesn’t happen.”

Chelsea and England winger Callum Hudson-Odoi, who was the subject of racist chants during the Three Lions’ victory in Montenegro in March, said: “It is disgusting to hear or see players getting discriminated against.

“It is not right. I say to myself, whenever that happens you have got to stick together as a team which the boys did.

“I am really proud to see the boys stick together and in those situations where they say they would walk off the pitch is right because no player should be treated differently.

“We are all equal. It is an equal game so we have all got to stay strong. Stay the same and the boys dealt with it well.

“Hopefully everything will be sorted properly by UEFA. Everything that happened was obviously not right but we have to stick together as a team and move on from it.”